The present invention relates to a method for navigating an autonomous vehicle that enables the autonomous vehicle to track a route accurately along passageways to a predetermined destination and to travel autonomously along the route. The present invention also relates to a device for navigating an autonomous vehicle using the aforementioned navigating method, and an autonomous vehicle provided with the navigating device using the navigating method.
Needs for so-called autonomous vehicles have been recognized in various industrial fields. The autonomous vehicle includes a self-motored vehicle having a power source, guided by sensors, for autonomously delivering goods to designated locations along routes on indoor or outdoor passageways, and a mobile carriage as part of robotic systems. However, the following requirements must be satisfied to navigate such an autonomous vehicle:
(1) The vehicle should by itself be able to measure and recognize its current position;
(2) The vehicle should by itself be able to track a route accurately along passageways leading itself to a destination; and
(3) The vehicle should by itself be able to autonomously guide itself along the found route.
Following conventional navigating methods are known for navigating autonomous vehicles:
(a) The vehicle is mounted with a camera, or an ultrasonic sensor, for visually observing and analyzing the surroundings of the vehicle and determines, based on the analysis result, a route to be followed that leads itself to a destination (the visual-image recognition method).
(b) Lines of light-reflecting tape are applied along passageways. The vehicle is mounted with a light-emitting device for lighting the light-reflecting tape and a light-detecting device for detecting the light reflection of the light-reflecting tape, thereby enabling the vehicle to track the light-reflecting tape. The light-reflecting tapes may be laid at intervals along passageways. As the vehicle travels, the vehicle counts, by a counter mounted on the vehicle, the number of tapes it has passed, and calculates the distance that the vehicle has traveled (the tape method).
(c) Cables generating an electromagnetic wave are laid continuously along passageways. An electromagnetic wave receiver is mounted on the vehicle for tracking the cables (the electromagnetic wave/cable method).
(d) Rail tracks are laid along passageways. The vehicle travels along the rail tracks (the rail-track method).
However, the visual-image recognition method has a problem that it requires a high-quality image processing device for analyzing complex backgrounds and contours of the vehicle""s surroundings. The tape method has a different problem that the tapes may become undetectable over years of use because of quality changes the tapes sustain due, for instance, to accumulation of dirt. The electromagnetic wave/cable method would cost significantly for laying cables. The rail track method also costs heavily for laying rails, and moreover, the rail tracks likely become obstacles for other traffics.
On the other hand, another method, using an RFID (Radio Frequency Identification Device), has been known. The RFID is a device that uses electromagnetic short wave (SW) to be exchanged between an information storing element and an information retrieving section as they come in proximity to each other, thereby supplying electricity from the information retrieving section to the information storing element and activating it, which transfers information (such as location data) stored therein to the information retrieving section where the data is then recognized.
One example of the FRID method described above is disclosed in the Official Gazette of Laid-open Japanese Patent Application No. Sho 62-501671.
The structure of the RFID in this application is similar to the structure shown in a block circuit diagram of FIG. 7. In FIG. 7, a numeral 71 indicates an information storing element comprising a memory 711 storing a variety of information (for example, location data indicating its location along a route, which data is also required in the present invention), a power circuit 712, a control circuit 713, a modular circuit 714, an antenna coil (antenna) 715, etc. The section comprising the control circuit 713 and the modular circuit 714 may be regarded as a transmitting/receiving circuit 11a. A numeral 72 indicates an information retrieving section comprising an oscillator circuit 721, a demodulating circuit 722, an antenna coil (antenna) 723, etc. The section consisting of the oscillator circuit 721 and the demodulating circuit 722 may be regarded as another transmitting/receiving circuit 11b. Although the information storing element 71 and the information retrieving section 72 are illustrated in the drawing at a distance therebetween, their respective antenna coils 715 and 723 come in proximity to each other in use. A numeral 73 indicates an information processing unit (computer) for processing information (data) which the information retrieving section 72 retrieved from the memory 711.
In order for the information retrieving section 72 to become able to retrieve information stored in the memory 711 of the information storing element 71, electricity has to be supplied from the information retrieving section 72 to the information storing element 71. For this purpose, the antenna coils 715 and 723 are first brought sufficiently close to each other, and the oscillator circuit 721 of the information retrieving section 72 is activated to oscillate, thus transmitting high-frequency electric current to the antenna coil 723. The antenna coil 723, in response, generates SW toward the antenna coil 715 of the information storing element 71. As a result, the antenna coils 723 and 715 become electromagnetically connected, and thus the high-frequency electric current is induced through the antenna coil 715. After converted at the power circuit 712, the electric current is supplied to the information storing element 71 in the form of electricity. This electricity activates the control circuit 713 to retrieve information (for example, location data) stored in the memory 711. Such information is then converted (modulated) by the modulating circuit 714 into high frequency electric current representing the information and transmitted from the antenna coil 715 toward the antenna coil 723 in the form of radio wave. The radio wave received by the antenna coil 723 of the information retrieving section 72 is then demodulated by the demodulating circuit 722 into the original information (such as location data) retrieved from the memory 711. The demodulated information is then sent to the computer 73 where the retrieved information is compared with a group of information (indicating, for instance, locations of information storing elements along passageways) stored in advance in the computer, and processed so that the information from the memory 711 is recognized and used for creating control signals.
The present invention relates to navigation of an autonomous vehicle and solves the problems of the aforementioned conventional navigating methods. It is an object of the present invention to reduce construction costs of navigation system facilities while providing long-term reliability to the navigating system.
It is another object of the present invention that when a vehicle is about to run off a route, it can detect such a status quickly and prevent the vehicle""s deviation from the route, and that it can also prevent navigation errors due to interferences of navigation radio waves.
According to the present invention, an autonomous vehicle is navigated along a route, using the functional concepts of the Radio Frequency Identification Device (RFID). The navigating method of the present invention comprising the steps of:
providing a route for a vehicle, formed with a plurality of elements, which correspond to the information storing element 71 of the RFID, in line along passageways on which the vehicle travels, each of the information storing element having a memory 711 storing in advance its own location information on the route;
mounting a component, which corresponds to the information retrieving section 72 of the RFID, on the vehicle so that as the vehicle travels, the information retrieving section 72 will come sufficiently close to the plurality of information storing elements 71 in sequence;
transmitting radio waves between the information retrieving section 72 and an information storing element 71;
supplying, through transmission of the radio wave, electricity from the vehicle to the information storing element 71 placed along the route to activating
the information storing element 71;
retrieving, by the information retrieving section 72 of the vehicle, the location information stored in the information storing element that indicates the present position of the vehicle; and
controlling a moving direction of the vehicle based on the position information to guide the vehicle along the route to a destination.
Another form of preferred embodiments of the present invention is a navigating method for navigating an autonomous vehicle, the method comprising the steps of:
providing a beacon line formed with a plurality of route beacons placed in line along a passageway, each beacon comprising: a memory storing its own location information on the route of a vehicle; an antenna for transmitting and receiving radio waves; a power circuit for converting the radio wave received by the antenna and supplying it as electricity; and a transmitting/receiving circuit, including the antenna, for receiving the radio wave, retrieving, powered by the power circuit, the beacon location information from the memory and transmitting the beacon location information by the antenna in the form of radio wave, the beacons being placed at specific locations corresponding to their respective location information,
on the vehicle having driving wheels and steering means for controlling its moving direction, mounting: a transmitting/receiving circuit, including an antenna for transmitting/receiving radio waves, for transmitting a radio wave toward the route beacon and for receiving a radio wave containing the location information thereof, thus obtaining the present position information of the vehicle therefrom; and a power source for operating the transmitting/receiving circuit, the driving wheels and the steering means for controlling a moving direction of the vehicle,
providing the vehicle further with a computer, in which information indicating locations of the route beacons to a destination is stored in advance, for executing computation, including comparing the retrieved vehicle""s position information with the information indicating locations of the route beacons;
controlling the steering means to control the moving direction based on a computation result;
supplying, through the transmission of the radio wave from the transmitting/receiving circuit of the vehicle, electricity from the vehicle to the beacons in sequence as the vehicle travels autonomously, thereby retrieving stored location information from the memory of the route beacon;
transmitting a radio wave containing the location information to the transmitting/receiving circuit of the vehicle in sequence;
receiving, by the transmitting/receiving circuit of the vehicle, the radio wave containing the location information and obtaining the vehicle""s present position information therefrom;
executing computation, by the computer, including comparing the vehicle""s present position information with the information indicating locations of the route beacons; and
controlling a moving direction of the vehicle based on the computation result to track the line of the route beacons, thereby guiding the autonomous vehicle along the route to the destination.
A second preferred embodiment form of the present invention is a navigating device for navigating an autonomous vehicle, comprising:
a plurality of route beacons, each beacon having: a memory storing its own location information in reference to a route of the vehicle; an antenna for transmitting and receiving radio waves; a power circuit for converting the radio wave received by the antenna and supplying it as electricity; and a transmitting/receiving circuit, including an antenna, for receiving a radio wave, retrieving, powered by the power circuit, the beacon location information from the memory, and transmitting the beacon location information by the antenna in the form of radio wave,
a route beacon line formed with the route beacons placed at specific locations corresponding to their respective location information;
a vehicle having driving wheels and steering means for controlling its moving direction;
a mobile transmitting/receiving circuit, including a radio wave transmitting/receiving antenna, for transmitting and receiving radio waves toward and from the route beacons and retrieving the beacon location information so as to obtain vehicle""s present position information therefrom;
a power source for operating the mobile transmitting/receiving circuit, the driving wheels and the steering means; and
a computer, in which information indicating locations of the route beacons to a destination is stored, for executing computation, including comparing the obtained vehicle""s position information with the information indicating locations of the route beacons, thereby controlling a moving direction of the steering means, the navigating device for the autonomous vehicle wherein the mobile transmitting/receiving circuit and the power source are mounted thereon.
A third preferred embodiment form of the present invention is an autonomous vehicle having a navigating device comprising:
a mobile transmitting/receiving circuit for transmitting a radio wave toward a plurality of route beacons, each route beacon comprising: a memory storing location information indicating its own location on a passageway; an antenna for transmitting and receiving radio waves; a power circuit for converting the radio wave received by the antenna into electricity and supplying it as power; and a transmitting/receiving circuit for receiving a radio wave, retrieving, powered by the power circuit, the location information from the memory and transmitting it by the antenna in the form of radio wave, the mobile transmitting/receiving circuit for receiving the radio wave from the route beacon and obtaining the vehicle""s present position information therefrom;
a power source required for operating the mobile transmitting/receiving circuit, driving wheels and steering means of the vehicle for controlling a moving direction of the vehicle; and
a computer, in which information indicating locations of the route beacons on the passageway to a destination is stored, for executing computation, including comparing the vehicle""s present position information with the information indicating locations of the route beacons, thereby controlling the steering means.